A phenomenon, in which application of a voltage to a material causes an oxidation-reduction reaction, so that reversible colorization or decolorization of a material occurs, is referred to as electrochromism. An electrochromic element (hereunder referred to as an EC element) designed to use a material exhibiting such a phenomenon and to cause the colorization and decolorization of the material by voltage operation is utilized in the fields of a display device and a light control device.
Meanwhile, EC elements include the liquid type and the solid type. The solid type EC elements excel in visibility, safety, and durability and are suitably used for automotive mirrors (for example, outside mirrors, inside mirrors, and door mirrors).
The solid type EC elements are usually formed on transparent substrates, such as glass and plastic plates. A schematic view of an automotive EC mirror using such an Ec element is illustrated in FIG. 4.
This EC mirror is provided with a lower transparent electrode (that is, a conductive layer) 3 serving as a first electrode, as illustrated in FIG. 4. ITO (indium tin oxide) film, SnO2 and so on are used as the materials of the electrode 3. For instance, a first EC layer 4 colored by a reduction reaction, an electrolytic layer 5, a second EC layer 6 colored by an oxidation reaction, and an upper-electrode and reflection film 7 (the materials of which are thin films made of metal, such as aluminum) are formed in sequence on this transparent electrode. A sealing material 8, which usually includes resins, such as an epoxy resin, and a sealing plate (or glass plate) 9 are superimposed thereon. Thus, an EC element is constructed.
For example, an iridium hydroxide (IRTOF) film is used as the first EC layer colored by a reduction reaction. For instance, a tungsten trioxide (WO3) film is used as the second EC layer colored by an oxidation reaction. For example, a layer made of tantalum pentaoxide (Ta2O5) is used as the electrolytic layer. Incidentally, the first and second EC layers may be constructed by replacing the material of the first EC layer with that of the second EC layer.
A lead-out electrode is usually needed for applying an external power supply to the lower electrode and the upper electrode of such an EC element. Hitherto, the substrate 1 and a lead-out electrode 3a for the lower electrode 3 are sandwiched and the substrate 1 and a lead-out electrode 7a for the upper electrode 7 are sandwiched by electrically conductive metallic clips 2 enabling favorable soldering of a harness. Moreover, the clips 2 and the harness 10 are soldered to one another.
Conventional clips are made of resilient materials in such a manner as not to easily slip off the substrate. Small metallic clips usually shaped in such a way as to have a channel-like section or a substantially-heart-like section and as to be narrow at entrance and wide at inner part thereof are frequently used as the conventional clips. However, such conventional metallic clips are usually formed from a thin material, such as phosphor bronze, which is low in electric resistance (usually, the metallic clips are formed so that the thickness thereof ranges 0.05 mm to 2 mm). Thus, elastic stress is insufficiently introduced thereto, so that the conventional shape thereof makes it difficult to exert a sandwiching force sufficient to the extent that the slip-off thereof is prevented.
Thus, the conventional clips are formed by infiltrating the sealing resin 8 into a gap 11 between a side piece of the clip 2 and the substrate 1 and fixing the clips 2 and the substrate 1 to each other by the sealing resin 8.
However, the sealing resin (for example, an epoxy resin) infiltrated into the gap 11 expands under a high temperature and humidity condition. This expanded sealing resin pushes up the terminal of the clip (see an explanatory view of an electrode portion of the clip when the sealing resin is expanded, which is illustrated in FIG. 5), poor contact between a conductive surface and the clip is liable to occur.
Further, when the clip is fitted onto the substrate, it is necessary to force the entrance of the clip open because the entrance of the clip is narrow. Thus, the workability of the conventional EC element is poor. Moreover, when the clip is fitted onto the substrate, the conductive surface is easily damaged. Furthermore, this metallic clip is easy to be deformed when fitted onto the substrate.
The invention is accomplished in view of the aforementioned circumstances. An object of the invention is to provide a structure enabled to prevent occurrences of troubles, such as poor contact between the conductive surface and the metallic clip of the EC element when the sealing resin expands, and to facilitate the fitting of the metallic clip onto the substrate.
That is, an object of the invention is to provide an electrode structure of an EC mirror, in which clip electrodes enabled to realize good workability of attaching the clips to the substrate, to prevent lead-out electrode portions from being damaged, and to increase a fitting force for fitting thereof to the substrate thereby to make the clips difficult to slip off the substrate are attached to lead-out electrodes of an EC element.